Gas turbine engines used in aircraft often include a fan assembly that is driven by an engine core to push air through the engine and provide thrust for the aircraft. A typical fan assembly includes a fan rotor having blades and a fan case that extends around the blades of the fan rotor. During operation, the fan blades of the fan rotor are rotated to push air through the engine. The fan case both guides the air pushed by the fan blades and provides a protective band that blocks fan blades from being thrown out of the fan assembly in case of a blade-off event in which a fan blade is released from the fan rotor.
Fan cases may optionally include sound attenuation devices (sometimes called dampers), and composite reinforcements (sometimes called fan case liners or fan track liners). Composite reinforcements, or fan case liners, are generally used to strengthen the fan cases and may be coupled to the metallic shrouds with adhesives.